Field of the Invention
The invention concerns a stacker device for flat items of the type having a receiving plate on which the flat items accumulate in a stack, a stop wall that stops movement of the flat items through the stacker, and a longitudinal wall against which the accumulated items rest in the stack.
Description of the Prior Art
Stacker devices of the above type are used in items processing systems or as a last station of a mail line, for example. A mail line of a franking system is composed of individual mail processing stations arranged serially, and the flat items are mail pieces. At the start of the mail line, a placement station may be designed that serves to place individual or stacked mail pieces, which are transported downstream (in terms of mail flow), through additional stations until the end of the mail line, at the stacker device. A stack of mail pieces of different formats (mixed mail) that has been placed at the placement station is individualized in the mail line by an immediately following (in the transport direction) separator device of a feed station, since further following mail processing stations require individually supplied mail pieces. The stacker device for a flat good is provided for a use in connection with items processing devices that precede the stacker device, such as mail processing stations in connection with franking machines, addressing machines and other mail processing stations.
As used herein, the term “mixed mail” means mail pieces of similar format that differ within boundaries of up to 10% in height and width, for example letters of the B6 (12.5×17.6 cm) and C6 (11.4×16.2 cm) formats.
The term “stack” in the following means a letter stack, postcard stack, mail piece stack or other stacked articles or stacked items that can be individualized, and will be supplied lying on their sides.
In the field of franking machines, solutions are known that transport a mail piece downstream (in terms of mail flow) in the transport direction so as to print with a franking imprint during the transport. A device for transferring mail items to a stacker device is known from EP 985 619 B1. However, the intake quantity of mail pieces of the stacker device is marginal. The stacker device is unsuitable to accept a larger quantity of mail pieces in an ordered fashion.
A stacker device for a larger quantity of stacked mail pieces is described in the following using the term “stack box”.
Such a box of smaller dimensions is known from JP 2000063026 A, for example. The base of the box is not inclined. A forward side wall can be opened like a door in order to remove the stack of mail pieces (postcards, for example). The problem of a high stack being at risk of tipping over exist for postcards of different formats, but not for postcards that are all of the same format.
In contrast, U.S. Pat. No. 6,648,284 B2 discloses an adjustment insert block within a items storage trough that has a base surface and a number of upright side walls that are connected with the base surface of the items storage trough. The adjustment insert block has a doubly inclined surface that produces an alignment of the stack of mail pieces at one corner of the items storage trough. A stack with mail pieces of different formats is thus also stored in an organized fashion in the items storage trough.
JP 2002234659 A discloses two wedge-shaped chamfers in the base of a box whose surface is inclined rearwardly, toward a guide wall, for the purpose of receiving paper sheets. A stop wall forms one end of the box that is directed downstream. In contrast to the start of the box, at the end of the box a guide wall protrudes into the region of flight paths of the paper sheets. A paper sheet on a maximum flight path therefore first strikes the guide wall and then falls onto the chamfers at the base of the box.
From U.S. Pat. No. 7,568,694 B2, a print medium collector is known that has a guide surface with an intake edge and an exit edge, wherein the guide surface is angled downwardly from the intake edge to the exit edge so that, when a printer releases an item to be printed that falls downwardly (due to gravity) over the exit edge onto the guide surface, and the item is moved with a leading edge of thereof within a region of flight paths, wherein each flight path has a downwardly directed and lateral component. A stop at the rear side of the print storage region may block a lateral movement of the item, so that such printed items are stored on a support surface against the stack, in order to form the stack. The aforementioned region of flight paths includes a maximum flight path in which the leading edge of the printed item is first contacts the stop and only afterward comes into contact with a printed item that is already lying on the support surface. The support surface is only slightly angled downwardly in the transport direction. The printed item collector is well suited for sheet-shaped print media of fixed length, but unsuited as a collector of mail pieces having differing formats (mixed mail).
From EP 1443008 B1, a device is known for receiving mail shipments in order to receive mail shipments that have been ejected via an exit slot of a folding and enveloping machine. The ejected mail shipments (which are stopped at a stop wall) collect on a support plate. Two side walls and one wall are designed to align these mail shipments again as soon as they have fallen onto the bearing plate. The wall has coupling means in order to enable a plugging of the receiving device onto the forward feed of a folding and enveloping machine. However, this receiving device is not entirely satisfactory because a uniform stack is not formed given a rapid ejection of mail pieces with identical format, due to an uncontrolled rebound.
In U.S. Pat. No. 8,590,888 B2, a storage device is described for storing mail pieces that are ejected from a franking machine out of an exit slot. The storage device has a receiving plate to receive mail pieces, a longitudinal alignment wall that extends across a longitudinal boundary of the receiving plate and perpendicular to the exit slot, on which the mail pieces strike before they collect on the receiving plate. The storage device has a vertical rear wall that extends along a lateral edge of the receiving plate, which the mail shipments meet before they strike against the longitudinal alignment wall. The vertical rear wall forms an angle β relative to a perpendicular line relative to the longitudinal alignment wall. The receiving plate is inclined at an angle φ relative to the horizontal and in the direction of the longitudinal alignment wall, such that the angle α between the receiving plate and the longitudinal alignment wall forms an acute angle of less than 90°. The longitudinal alignment wall is inclined at an angle Δ relative to the vertical direction and downwardly from the receiving plate. The production of the storage device is complicated because the bending of the longitudinal alignment wall over the longitudinal boundary of the receiving plate takes place with a curve, and all aforementioned angles α, β, Δ and φ are acute angles. Given a medium-speed ejection of mail shipments with differing formats (mixed mail), it is not guaranteed that a stack will be formed in an organized fashion, and cannot tip over. The stacks tend to tip over as of a specific height. The receiving plate has a boundary wall raised upwardly at the front side, but this is only effective for a very small stack height. The device is unsuited for the receiving and organized collection of mixed mail. Due to the curves at the receiving plate, mail pieces of different sizes cannot align themselves on an edge, in particular if the lowermost mail piece of the stack has a very small format. The placed mail pieces cannot always be removed without problems. The boundary wall that is raised at the front side interferes with the removal of the stack from the storage device. A predetermined piece count of mail pieces can in fact be franked and ejected via an adjustment to the franking machine. However, in the case of mixed mail, the removed stack may have a different stack height that is dependent on the thickness of the mail pieces. An additional disadvantage is that the mail pieces cannot be stacked to a desired stack height at which the stack can easily be grasped by hand.